#2 "Worth slightly less is a 1943 copper penny (supposed to be steel)." Except for this one...... One 1943 copper-alloy penny is the only known 1943 copper penny produced in the Denver mint and sold for $1.7 million in 2010, while other 1943 copper pennies are worth in excess of $50,000, depending on condition. During World War II, the war effort needed copper and zinc, so the 1943 penny featured steel, but a few copper-alloy blanks were still in the hoppers at the mints. Because of the value, enterprising forgers cover 1943 steel pennies with a layer of copper. A magnet reveals a forgery; if the penny sticks, it is a fake.
The 1944 steel penny is also a mistake, with a value sometimes approaching $100,000, depending on condition. The U.S. Mint changed the coin's composition back from steel to a modified copper alloy made from used shell casings, but some steel blanks left in the hopper resulted in rare 1944 steel pennies.